The cancer‐related transcription factor Runx2 modulates cell proliferation in human osteosarcoma cell lines

Runx2 regulates osteogenic differentiation and bone formation, but also suppresses pre‐osteoblast proliferation by affecting cell cycle progression in the G₁ phase. The growth suppressive potential of Runx2 is normally inactivated in part by protein destabilization, which permits cell cycle progression beyond the G₁/S phase transition, and Runx2 is again up‐regulated after mitosis. Runx2 expression also correlates with metastasis and poor chemotherapy response in osteosarcoma. Here we show that six human osteosarcoma cell lines (SaOS, MG63, U2OS, HOS, G292, and 143B) have different growth rates, which is consistent with differences in the lengths of the cell cycle. Runx2 protein levels are cell cycle‐regulated with respect to the G₁/S phase transition in U2OS, HOS, G292, and 143B cells. In contrast, Runx2 protein levels are constitutively expressed during the cell cycle in SaOS and MG63 cells. Forced expression of Runx2 suppresses growth in all cell lines indicating that accumulation of Runx2 in excess of its pre‐established levels in a given cell type triggers one or more anti‐proliferative pathways in osteosarcoma cells. Thus, regulatory mechanisms controlling Runx2 expression in osteosarcoma cells must balance Runx2 protein levels to promote its putative oncogenic functions, while avoiding suppression of bone tumor growth. J. Cell. Physiol. 228: 714–723, 2013. © 2012 Wiley Periodicals, Inc.     

Overexpression of TTRAP inhibits cell growth and induces apoptosis in osteosarcoma cells

TTRAP is a multi-functional protein that is involved in multiple aspects of cellular functions including cell proliferation, apoptosis and the repair of DNA damage. Here, we demonstrated that the lentivirus-mediated overexpression of TTRAP significantly inhibited cell growth and induced apoptosis in osteosarcoma cells. The ectopic TTRAP suppressed the growth and colony formation capacity of two osteosarcoma cell lines, U2OS and Saos-2. Cell apoptosis was induced in U2OS cells and the cell cycle was arrested at G2/M phase in Saos-2 cells. Exogenous expression of TTRAP in serum-starved U2OS and Saos-2 cells induced an increase in caspase-3/-7 activity and a decrease in cyclin B1 expression. In comparison with wild-type TTRAP, mutations in the 5''-tyrosyl-DNA phosphodiesterase activity of TTRAP, in particular TTRAP^E152A, showed decreased inhibitory activity on cell growth. These results may aid in clarifying the physiological functions of TTRAP, especially its roles in the regulation of cell growth and tumorigenesis. [BMB Reports 2013; 46(2): 113-118]     

甲硫氨酸限制对骨肉瘤细胞增殖、凋亡及铁死亡的影响

摘要 目的：探讨甲硫氨酸限制对骨肉瘤细胞增殖,凋亡和铁死亡的影响。方法：使用细胞计数检测剥夺甲硫氨酸对三株不同的骨肉瘤细胞系增殖的影响;高通量测序（RNA-seq）分析甲硫氨酸限制后骨肉瘤细胞的转录组学变化;流式细胞术检测细胞周期,凋亡以及ROS,脂质ROS水平;Western blot检测铁死亡关键蛋白谷胱甘肽过氧化物GPX4以及铁死亡标志蛋白前列腺素内过氧化物合成Cox-2的表达。结果：甲硫氨酸限制显著抑制骨肉瘤细胞的增殖（P<0.001）;RNA-seq分析筛选出1719个差异表达基因,基因富集分析发现甲硫氨酸限制可显著激活铁死亡通路并显著抑制细胞周期通路;细胞实验证实甲硫氨酸限制将骨肉瘤细胞阻滞在G2M期,显著诱导凋亡细胞比例增加;同时,细胞内Cox-2的表达增加,GPX4的活性降低,活性氧和脂质活性氧积累,最终导致细胞死亡,且这种作用可以被铁死亡抑制剂Fer-1部分挽救。结论：本研究的结果为甲硫氨酸限制治疗骨肉瘤提供了一定的科学依据。     

Inducible expression of the regulatory protein kinase CK2β subunit: Incorporation into complexes with catalytic CK2 subunits and re‐examination of the effects of CK2β on cell proliferation

The regulatory subunit of protein kinase CK2, designated CK2β, exists both free in cells and in complexes with the CK2 catalytic subunits. Growing evidence suggests that CK2β has functions dependent and independent of the CK2 catalytic subunits. There have been indications that CK2β has functions associated with DNA damage responses and in the control of cell proliferation. For example, transient and stable constitutive overexpression of CK2β in mammalian cells was previously shown to perturb cell cycle progression and to attenuate proliferation. To systematically investigate the molecular mechanisms responsible for these effects of CK2β on cell proliferation, we generated human osteosarcoma U2OS cell lines with tetracycline‐regulated expression of CK2β. Increased expression of CK2β results in increases in total cellular CK2 activity, but no changes in cell cycle profiles or proliferation. Furthermore, following exposure to ultraviolet radiation, p53 induction was identical regardless of the levels of CK2β in cells. Mouse 3T3‐L1 cells stably transfected with CK2β also showed no alterations in cell proliferation. The differences between these results and those previously reported emphasize the complex nature of CK2β and its cellular functions. Furthermore, these results indicate that increased expression of CK2β is not by itself sufficient to effect alterations in cell proliferation. J. Cell. Biochem. 84: 84–99, 2002. © 2001 Wiley‐Liss, Inc.     

Tumor-Suppressing Effects of miR451 in Human Osteosarcoma

Osteosarcoma is the 3rd most common human cancer in childhood and young adults, and is the leading cause of mortality. Recent studies suggest that miRNAs could regulate the growth and progression of osteosarcoma, indicating some novel targets for therapy. In our study, we demonstrated that miR-451 was down-regulated in human osteosarcoma U2OS, SAOS, and MG63 cells lines as well as in tumor tissue surgically resected compared with the normal tissues. Overexpression of miR-451 inhibited cell proliferation and resulted in cell apoptosis in osteosarcoma cells. G1 cell cycle arrest was also induced by miR-451. Repressed by miR-451, PGE2 and CCND1 reversed the inhibitory effects of miR-451 on proliferation. In conclusion, miR-451 played a tumor-suppressing role through modulating the expression of PGE2 and CCND1, suggesting a novel target for the diagnosis and treatment of osteosarcoma.     

Inorganic phosphate enhances sensitivity of human osteosarcoma U2OS cells to doxorubicin via a p53‐dependent pathway

Osteosarcoma is the most common malignant primary bone tumor in children and adolescents. The clinical outcome for osteosarcoma remains discouraging despite aggressive surgery and intensive radiotherapy and chemotherapy regimens. Thus, novel therapeutic approaches are needed. Previously, we have shown that inorganic phosphate (Pi) inhibits proliferation and aggressiveness of human osteosarcoma U2OS cells identifying adenylate cyclase, beta3 integrin, Rap1, ERK1/2 as proteins whose expression and function are relevantly affected in response to Pi. In this study, we investigated whether Pi could affect chemosensitivity of osteosarcoma cells and the underlying molecular mechanisms. Here, we report that Pi inhibits proliferation of p53‐wild type U2OS cells (and not of p53‐null Saos and p53‐mutant MG63 cells) by slowing‐down cell cycle progression, without apoptosis occurrence. Interestingly, we found that Pi strongly enhances doxorubicin‐induced cytotoxicity in U2OS, and not in Saos and MG63 cells, by apoptosis induction, as revealed by a marked increase of sub‐G1 population, Bcl‐2 downregulation, caspase‐3 activation, and PARP cleavage. Remarkably, Pi/doxorubicin combination‐induced cytotoxicity was accompanied by an increase of p53 protein levels and of p53 target genes mdm2, p21 and Bax, and was significantly reduced by the p53 inhibitor pifithrine‐alpha. Moreover, the doxorubicin‐induced cytotoxicity was associated with ERK1/2 pathway inhibition in response to Pi. Altogether, our data enforce the evidence of Pi as a novel signaling molecule capable of inhibiting ERK pathway and inducing sensitization to doxorubicin of osteosarcoma cells by p53‐dependent apoptosis, implying that targeting Pi levels might represent a rational strategy for improving osteosarcoma therapy. J. Cell. Physiol. 228: 198–206, 2013. © 2012 Wiley Periodicals, Inc.     

circ_0001461靶向抑制miR-30a-5p对骨肉瘤细胞增殖和凋亡的影响

摘要 目的：探讨circ_0001461对骨肉瘤细胞增殖和凋亡的影响及调控机制。方法：采用实时荧光定量聚合酶反应（qRT-PCR）检测检测circ_0001461在骨肉瘤组织和细胞中的表达水平。在U2OS和HOS细胞中转染sh-NC和sh-circ_0001461后,采用CCK8检测细胞增殖情况,流式细胞术检测细胞凋亡情况,qRT-PCR检测增殖相关分子Ki-67 mRNA的表达水平,Western Blot检测凋亡相关分子Cleaved-caspase-3蛋白的表达水平。采用双荧光素酶报告基因检测circ_0001461和miR-30a-5p的结合情况。结果：circ_0001461在骨肉瘤组织中的表达水平明显高于癌旁正常组织（P<0.05）,circ_0001461在骨肉瘤细胞U2OS和HOS中的表达水平均明显高于成骨细胞NHOst（P<0.05）。低表达circ_0001461能够抑制骨肉瘤细胞U2OS和HOS的增殖和增殖相关分子Ki-67的表达（P<0.05）;促进骨肉瘤细胞U2OS和HOS的凋亡和凋亡相关分子Cleaved-caspase-3蛋白的表达（P<0.05）。双荧光素酶结果显示circ_0001461能够靶向结合miR-30a-5p。低表达circ_0001461能够促进miR-30a-5p的表达（P<0.05）,circ_0001461和miR-30a-5p在骨肉瘤组织中的表达呈负相关（P<0.05）。在U2OS细胞中共转染sh-circ_0001461和miR-30a-5p mimics后能够进一步加强单独转染sh-circ_0001461对U2OS细胞增殖和凋亡的影响（P<0.05）;在HOS细胞中共转染sh-circ_0001461和miR-30a-5p inhibitors后能够逆转单独转染sh-circ_0001461对U2OS细胞增殖和凋亡的影响（P>0.05）。结论：circ_0001461在骨肉瘤组织和细胞中明显高表达,低表达circ_0001461能够靶向促进miR-30a-5p的表达进而抑制骨肉瘤细胞增殖和促进细胞凋亡。     

Inducible expression of the regulatory protein kinase CK2beta subunit: incorporation into complexes with catalytic CK2 subunits and re-examination of the effects of CK2beta on cell proliferation.

The regulatory subunit of protein kinase CK2, designated CK2beta, exists both free in cells and in complexes with the CK2 catalytic subunits. Growing evidence suggests that CK2beta has functions dependent and independent of the CK2 catalytic subunits. There have been indications that CK2beta has functions associated with DNA damage responses and in the control of cell proliferation. For example, transient and stable constitutive overexpression of CK2beta in mammalian cells was previously shown to perturb cell cycle progression and to attenuate proliferation. To systematically investigate the molecular mechanisms responsible for these effects of CK2beta on cell proliferation, we generated human osteosarcoma U2OS cell lines with tetracycline-regulated expression of CK2beta. Increased expression of CK2beta results in increases in total cellular CK2 activity, but no changes in cell cycle profiles or proliferation. Furthermore, following exposure to ultraviolet radiation, p53 induction was identical regardless of the levels of CK2beta in cells. Mouse 3T3-L1 cells stably transfected with CK2beta also showed no alterations in cell proliferation. The differences between these results and those previously reported emphasize the complex nature of CK2beta and its cellular functions. Furthermore, these results indicate that increased expression of CK2beta is not by itself sufficient to effect alterations in cell proliferation.     

Decreased expression of SATB2: a novel independent prognostic marker of worse outcome in laryngeal carcinoma patients

Background

To investigate the expression and role of special AT-rich sequence-binding protein-2 (SATB2) in laryngeal squamous cell carcinoma (LSCC) tissue and cell line (HEp2), and to evaluate the clinical and prognostic significance of SATB2 protein in patients with LSCC.

Methods

The expression of SATB2 was examined in LSCC tissue and HEp2 cells by Western-blotting, Real-time PCR and immunohistochemical staining. Cell growth curve assay and colony formation assay were used to verify the effect of SATB2 on the proliferation and tumor progression ability of HEp2 cells. Tumor formation assay in nude mice was used to analyze the effect of SATB2 on the tumorigenicity of HEp2 cells.

Results

The status of SATB2 protein in carcinoma tissues is much lower than that in paracarcinoma tissues. The overall survival of the patients with high SATB2 expression was significantly higher than the low SATB2 expression group. Lower or negative SATB2 expression was significantly correlated with advanced clinical staging, histological grade and tumor recurrence. In vitro experiments demonstrated that over-expression of SATB2 in HEp2 cells inhibited cell proliferation and tumor progression ability, and down-regulation of SATB2 showed the opposite effects. Over-expression of SATB2 repressed the tumorigenicity of HEp2 cells by in vivo experiments. Moreover, multivariate analysis suggested that SATB2 expression might be an independent prognostic indicator for the survival of LSCC patients after curative surgery.

Conclusions

SATB2 might involve in the development and progression of LSCC as a tumor suppressor, and thereby may be a valuable prognostic marker for LSCC patients.     

BMP-2、-3、-6和-12在骨肉瘤细胞株中的表达

目的研究骨形态发生蛋白(bone morphogenetic protein,BMP)-2、-3、-6和-12在骨肉瘤细胞株中的表达,为下一步研究BMPs在骨肉瘤发生发展中的作用奠定基础。方法利用免疫细胞化学法和Western blot法检测BMP-2、-3、-6和-12在人骨肉瘤细胞株MG63、U2OS和大鼠骨肉瘤细胞株UMR106中的内源性表达。结果在MG63、U2OS和UMR106细胞中,BMP-2、-3和-6均呈不同程度的阳性表达;而BMP-12在这3株骨肉瘤细胞中则均为阴性,并且两种检测方法所得结果完全一致。结论BMP-2、-3和-6在人骨肉瘤细胞株MG63、U2OS和大鼠骨肉瘤细胞株UMR106中均有内源性表达;而这3株骨肉瘤细胞中均未检出BMP-12的表达。     

转录因子HBP1调控H2O2诱导的骨肉瘤细胞生长阻滞过程

为探讨氧化应激对人骨肉瘤细胞增殖的影响及其作用机理,首先用H2O2处理U2OS细 胞,采用Western印迹和real-time PCR检测HMG盒转录因子1 (HBP1)及其下游靶基因 DNMT1和p16表达水平的变化. 用荧光素酶报告基因实验检测在H2O2诱导下, HBP1对于DNMT1 和p16启动子的影响. 用细胞增殖试验（BrdU掺入,细胞生长曲线）检测 H2O2对细胞增殖的影响以及HBP1的作用. 用衰老相关β半乳糖苷酶(SA-β-Gal)染色 检测在H2O2诱导的细胞衰老中HBP1所起的作用. Western 印迹, real-time PCR及荧光素酶报告基因实验结果显示,细胞经H2O2处理后,明显增高HBP1表达水平,转录抑制DNMT1的表达, 促进p16蛋白的表达. 细胞增殖实验结果显示, H2O2显著抑制了细胞的增殖,HBP1 knockdown可部分逆转这种抑制作用. SA-β-Gal染色实验说明, H2O2可诱导HBP1表达正常的U2OS细胞衰老,而HBP1 knockdown使这种促衰老作用减弱. 研究结果说明, H2O2可抑制人骨肉瘤细胞增殖,诱导细胞衰老. 其作用机制是通过上调转录因子HBP1的表达,转录抑制或促进其下游靶基因DNMT1或p16的表达来抑制细胞增殖,促进细胞衰老.     

Association of RDM1 with osteosarcoma progression via cell cycle and MEK/ERK signalling pathway regulation

RAD52 motif-containing 1 (RDM1), a key regulator of DNA double-strand break repair and recombination, has been reported to play an important role in the development of various human cancers, such as papillary thyroid carcinoma, neuroblastoma and lung cancer. However, the effect of RDM1 on osteosarcoma (OS) progression remains unclear. Here, this study mainly explored the connection between RDM1 and OS progression, as well as the underlying mechanism. It was found that RDM1 was highly expressed in OS cells compared with human osteoblast cells. Knockdown of RDM1 caused OS cell proliferation inhibition, cell apoptosis promotion and cell cycle arrest at G1 stage, whereas RDM1 overexpression resulted in the opposite phenotypes. Furthermore, RDM1 silencing leads to a significant decrease in tumour growth in xenograft mouse model. RDM1 also increased the protein levels of MEK 1/2 and ERK 1/2. All these findings suggest that RDM1 plays an oncogenic role in OS via stimulating cell cycle transition from G1 to S stage, and regulating MEK/ERK signalling pathway, providing a promising therapeutic factor for the treatment of OS.     

盐酸罗哌卡因对骨肉瘤细胞增殖、侵袭、凋亡的影响及其机制*

目的:探讨盐酸罗哌卡因对骨肉瘤细胞增殖、侵袭、凋亡的影响及分子机制。方法:采用逐步增加药物剂量诱导法建立骨肉瘤多柔比星耐药细胞株(U2OS/DOX),用浓度分别为0、20、50、100 μg/ml的盐酸罗哌卡因处理U2OS/DOX细胞,作为不同浓度盐酸罗哌卡因处理组;将pcDNA3.1、pcDNA3.1-Livin转染至U2OS/DOX细胞中再用浓度为100 μg/ml的盐酸罗哌卡因处理,记为盐酸罗哌卡因100 μg/ml+pcDNA3.1组、盐酸罗哌卡因100 μg/ml+pcDNA3.1-Livin组。MTT检测细胞增殖抑制率及细胞半数抑制浓度(IC₅₀);蛋白质印迹(Western blot)法检测细胞周期蛋白依赖性激酶抑制剂1A(P21)、活化的半胱氨酸天冬氨酸蛋白酶-3(Cleaved Caspase-3)、上皮钙黏蛋白(E-cadherin)、基质金属蛋白酶2(MMP-2)、Livin蛋白表达;克隆形成实验检测细胞克隆形成数;流式细胞术检测细胞凋亡;Transwell检测细胞迁移和侵袭;实时荧光定量PCR(RT-qPCR)检测Livin mRNA表达水平。结果:多柔比星浓度大于1 μg/ml时,骨肉瘤细胞U2OS增殖抑制率显著升高,且具有剂量依赖性(P＜0.05);多柔比星浓度大于10 μg/ml时,骨肉瘤细胞骨肉瘤耐药细胞U2OS/DOX增殖抑制率显著升高,且具有剂量依赖性(P＜0.05)。盐酸罗哌卡因处理的U2OS/DOX细胞中P21、Caspase-3、E-cadherin表达水平显著升高,MMP-2表达水平显著降低,细胞增殖抑制率显著升高,克隆形成数显著降低,细胞凋亡率显著升高,细胞迁移、侵袭数显著降低,Livin表达水平显著降低,且呈浓度依赖性(P＜0.05)。过表达Livin部分逆转了盐酸罗哌卡因对细胞U2OS/DOX增殖、迁移、侵袭的抑制作用及凋亡的促进作用。结论:盐酸罗哌卡因能明显抑制对多柔比星具有耐药性的骨肉瘤细胞的增殖,迁移和侵袭,明显促进骨瘤细胞凋亡,其机制可能与Livin有关。     

Apoptotic effect and cell arrest of deoxyshikonin in human osteosarcoma cells through the p38 pathway

Osteosarcoma is the most common primary bone cancer that affects adolescents with early metastatic potential and drastically reduces their long-term survival rate if pulmonary metastases are detected at diagnosis. The natural naphthoquinol compound deoxyshikonin exhibits anticancer properties, so we hypothesized that it has an apoptotic effect on osteosarcoma U2OS and HOS cells and studied its mechanisms. After deoxyshikonin treatment, dose-dependent decreases in cell viability, induction of cell apoptosis and arrest in the sub-G1 phase of U2OS and HOS cells were observed. The increases in cleaved caspase 3 expression and the decreases in X-chromosome-linked IAP (XIAP) and cellular inhibitors of apoptosis 1 (cIAP-1) expressions after deoxyshikonin treatment in the human apoptosis array were identified in HOS cells, and dose-dependent expression changes of IAPs and cleaved caspase 3, 8 and 9 were verified by Western blotting in U2OS and HOS cells. Phosphorylation of extracellular signal-regulated protein kinases (ERK)1/2, c-Jun N-terminal kinases (JNK)1/2 and p38 expressions in U2OS and HOS cells was also increased by deoxyshikonin in a dose-dependent manner. Subsequently, cotreatment with inhibitors of ERK (U0126), JNK (JNK-IN-8) and p38 (SB203580) was performed to show that p38 signalling is responsible for deoxyshikonin-induced apoptosis in U2OS and HOS cells, but not via the ERK and JNK pathways. These discoveries demonstrate that deoxyshikonin may be a possible chemotherapeutic candidate to induce cell arrest and apoptosis by activating extrinsic and intrinsic pathways through p38 for human osteosarcoma.     

Increased invasiveness of osteosarcoma mesenchymal stem cells induced by bone-morphogenetic protein-2

To evaluate the different traits of mesenchymal stem cell (MSC) isolated from osteosarcoma (OS) and normal bone marrow (BM) induced by bone-morphogenetic protein-2 (BMP-2). MSCs from implanted osteosarcoma or femur bone marrow were isolated and cultured. Differentiation potency was verified and phenotypes were evaluated by flow cytometry. Increased or decreased expressions of BMP-2 were delivered by adenovirus and lentivirus vector, respectively. Expressions of VEGF, EMMPRIN, and MMP-9 were examined. Cell cycle, apoptosis, invasiveness, and proliferation assays were performed between the transfected groups and controls. Increased BMP-2 induced over-expression of VEGF, EMMPRIN, and MMP-9 in OS- and BM-MSCs both intra- and extra-cellularly. Decreased BMP-2 expression induced inhibition of the factors. Increased BMP-2 also induced less population of cells at G1 phase, more apoptotic cells, more cells that invade through Transwell membrane, and faster proliferation in OSMSC compared to those in BMMSC. BMP-2 induced higher expression of tumorigenic factors, which could be responsible for promoting the proliferation and aggressiveness of OSMSC over BMMSC.     

microRNA-143 is associated with the survival of ALDH1+CD133+ osteosarcoma cells and the chemoresistance of osteosarcoma

This study investigated the role of miR-143 in the chemoresistance of osteosarcoma tumor cells and the associated mechanisms. Real-time PCR was used to measure miR-143 levels. Western blot was used to detect protein expression. Cell proliferation was analyzed by MTT assay and Matrigel colony formation assay. Forced miR-143 expression was established by adenoviral vector infection. Cell death was detected by Hoechst33342 staining. Loss of miR-143 expression was observed in osteosarcomas, which correlated with shorter survival of patients with osteosarcomas underlying chemotherapy. In chemoresistant SAOS-2 and U2OS osteosarcomas cells, miR-143 levels were significantly downregulated and accompanied by increases in ATG2B, Bcl-2, and/or LC3-II protein levels, high rate of ALDH1⁺CD133⁺ cells, and an increase in Matrigel colony formation ability. H₂O₂ upregulated p53 and miR-143, but downregulated ATG2B, Bcl-2, and LC3-I expression in U2OS cells (wild-type p53) but not in SAOS-2 (p53-null) cells. Forced miR-143 expression significantly reversed chemoresistance as well as downregulation of ATG2B, LC3-I, and Bcl-2 expression in SAOS-2- and U2OS-resistant cells. Forced miR-143 expression significantly inhibited tumor growth in xenograft SAOS-2-Dox and U2OS-Dox animal models. Loss of miR-143 expression is associated with poor prognosis of patients with osteosarcoma underlying chemotherapy. The chemoresistance of osteosarcoma tumor cells to doxorubicin is associated with the downregulation of miR-143 expression, activation of ALDH1⁺CD133⁺ cells, activation of autophagy, and inhibition of cell death. miR-143 may play a crucial role in the chemoresistance of osterosarcoma tumors.     

Upregulation of microRNA-7 contributes to inhibition of the growth and metastasis of osteosarcoma cells through the inhibition of IGF1R

We aim to uncover the methylation of microRNA-7 (miR-7) promoter in osteosarcoma (OS) and the inner mechanism of miR-7 on the progression of OS cells. Expression and methylation state of miR-7 in OS tissues and cells were detected. With the aim to unearth the ability of miR-7 in OS, the proliferation, cell cycle progression, apoptosis, invasion, migration of OS cells, and the tumor growth in nude mice were determined. Meanwhile, IGF1R expression was detected and the association between miR-7 and IGF1R was confirmed. The proliferating cell nuclear antigen (PCNA) expression was tested by immunohistochemical staining, and the lung metastasis was observed by H&E staining. miR-7 expression was decreased and methylation state of miR-7 was increased in OS tissues and cells. Upregulated miR-7 inhibited proliferation, cell cycle progression, invasion,and migration, while inducing apoptosis of OS cells and the tumor growth as well as PCNA expression in nude mice. Expression of IGF1R was downregulated in OS cells with overexpression of miR-7. Experiments verified the binding site between miR-7 and IGF1R. Our study demonstrates that abnormal methylation of miR-7 contributes to decreased miR-7 in OS. In addition, miR-7 represses the initiation and progression of OS cells through the inhibition of IGF1R.